A spark plug causes a spark discharge at a gap between a distal end of a center electrode and a distal end of a ground electrode when a voltage is applied to the center electrode and the ground electrode, which are insulated from each other by an insulator. There is a known technology in which an electrode tip that is made of a noble metal or the like, which has good antiwear properties, is used to improve the durability of an electrode (for example, Japanese Unexamined Patent Application Publication No. 2003-229231). In the technology described in Japanese Unexamined Patent Application Publication No. 2003-229231, a ground electrode tip is resistance welded to a ground electrode body, which is made of a nickel alloy.
However, with the technology described above, there is a possibility that the strength of a resistance weld may decrease due to an irregularity in the pressure between the electrode tip and the electrode body during resistance welding. As a result, there is a possibility that peeling of an electrode tip may occur more easily and the durability of the spark plug may decrease.
An advantage of the present invention is to suppress peeling of electrode tips and improve spark plug durability.